Marine Conservation Society volunteers clean a beach. The charity says the 40% drop is the lowest number in the past decade.
Photograph: Marine Conservation Society

The number of plastic carrier bags found on UK beaches has dropped by almost half, according to conservationists.

The Marine Conservation Society said the introduction of a 5p levy on single-use plastic bags in England, Scotland, Wales and Northern Ireland over the past five years was instrumental in the reduction.

According to the charity’s annual Great British Beach Clean report, there were 11 plastic bags per 100 metres of coastline cleaned in 2015, on average. This year, however, there was just under seven, which is a decrease of almost 40% and the lowest number in the past 10 years.

The charity began calling for action on single-use carrier bags in shops back in 2008 and was instrumental in getting a levy introduced in Wales in 2011, Northern Ireland in 2013, Scotland in 2014 and England last October.

The charity’s beach watch manager, Lauren Eyles, said: “In the last decade, our Great British Beach Clean volunteers have found an average of 10 single use carrier bags for every 100 metres of coastline cleaned.

“It vindicates the charge, which we predicted would be good news for the marine environment. Thanks to our thousands of fantastic volunteers who collect beach litter data, we can now see the impact these charges have had.”

Beaches in England and Northern Ireland saw the biggest drop in the number of plastic bags found during the September cleanup – more than half compared with 2015.

In Wales, where the charge has been in place for five years, there were just under four bags for every 100 metres cleaned. This number is significantly lower than any other year since 2011. In Scotland, volunteers found, on average, one bag fewer over the same distance this year compared with last year.

The charity said there has been a drop of almost 4% in the amount of litter found on UK beaches between 2015 and 2016, with 6,000 volunteers collecting 268,384 items.

Beaches in Scotland saw a decrease of 18% in overall litter levels, rubbish innorth-east England dropped by 14% and in the Channel Islands by 10%. But there were increases in the amount of beach litter in the north-west (24%), Wales and the south-west (15%) and in Northern Ireland (9%).

Analysis of the data collected by volunteers also showed a rise of more than 4% in the quantity of drinks containers found on the UK’s beaches. This included including plastic bottles, bottle tops and aluminium cans.

There was also a 53% rise over the past year in the amount of balloon-related litter found on beaches.

Turtles mistake plastic bags and balloons for their jellyfish prey, and the items can block their digestive systems, leading to death from starvation. Some species of seabirds are particularly attracted by the scent of this plastic junk “food”.